U.S. patent number 5,115,654 [Application Number 07/452,617] was granted by the patent office on 1992-05-26 for expansion apparatus having three borehole-channel systems.
This patent grant is currently assigned to Emitec Gesellschaft fur Emissionstechnologie mbH. Invention is credited to Wolfgang Maus, Helmut Swars.
United States Patent |
5,115,654 |
Swars , et al. |
May 26, 1992 |
Expansion apparatus having three borehole-channel systems
Abstract
A process for allowing the attachment of drive or coupling
elements, such as cams, gears, crank webs or bearing elements, such
as friction bearing bushes, or complete roller bearings on tubes or
tubular portions by hydraulic expansion, for the purpose of
producing assembled cam shafts, transmission shafts, crank shafts
or the like, with the expansion of the tubes taking place
exclusively in the region of the respective elements beyond the
limit of elasticity of the tubes, against a permanent elastic
prestress in the elements. To relieve the load on the seals
limiting the regions to be expanded, a counter pressure which is
higher than the ambient pressure is applied to the intermediate or
end regions.
Inventors: |
Swars; Helmut (Bergisch
Gladbach, DE), Maus; Wolfgang (Bergisch Gladbach,
DE) |
Assignee: |
Emitec Gesellschaft fur
Emissionstechnologie mbH (Lohmar, DE)
|
Family
ID: |
6369441 |
Appl.
No.: |
07/452,617 |
Filed: |
December 18, 1989 |
Foreign Application Priority Data
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Dec 17, 1988 [DE] |
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3842589 |
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Current U.S.
Class: |
72/62; 29/523;
29/283.5; 29/421.1; 72/61 |
Current CPC
Class: |
B21D
39/203 (20130101); B21D 53/845 (20130101); Y10T
29/49805 (20150115); Y10T 29/53996 (20150115); Y10T
29/4994 (20150115) |
Current International
Class: |
B21D
39/20 (20060101); B21D 53/84 (20060101); B21D
53/00 (20060101); B21D 39/08 (20060101); B21D
026/02 () |
Field of
Search: |
;29/252,283.5,421.1,464,506,507,508,516,522.1,523 ;72/58,61,62 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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372608 |
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Feb 1988 |
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DE |
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54-77272 |
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Jun 1979 |
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JP |
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8700457 |
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Jan 1987 |
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WO |
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2206515 |
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Jan 1989 |
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GB |
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2207071 |
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Jan 1989 |
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GB |
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Primary Examiner: Gorski; Joseph M.
Assistant Examiner: Vo; Peter Dungba
Attorney, Agent or Firm: Toren, McGeady & Associates
Claims
What is claimed as new and desired to be protected by letters
patent is set forth in the appended claims.
1. An apparatus for radially expanding a tubular member,
comprising:
an elongated pressure agent probe having separate first, second and
third internal channels each having an open end and a closed end
and extending longitudinally of the probe;
first, second and third radial boreholes extending from the first,
second and third internal channels, respectively, to an external
surface of the probe;
a plurality of circumferential seals mounted on said external
surface in longitudinally spaced relation, each of said first
boreholes opening into said external surface between an adjacent
pair of seals which define between them an effective region for
expansion of said tubular member, each said second boreholes
opening into said external surface at first intermediate regions
immediately adjacent to and on each side of said effective regions,
each first intermediate region being defined between one of the
seals which defines its adjacent effective region and another seal
which does not define an effective region, said third boreholes
opening into said external surface in second intermediate regions
each defined between said other seals which are arranged
successively longitudinally of the probe and in end regions defined
between said ends of the probe and said other seals of the first
intermediate regions adjacent to said ends;
a first, higher pressure source of pressure agent connected to the
open end of said first channel; and
a second lower pressure source and a third lower pressure source of
pressure agent connected to the open ends of said second and third
channels, respectively.
Description
BACKGROUND OF THE INVENTION
The invention relates to a process for allowing the attachment of
drive or coupling elements, such as cams, gears, crank webs, or
bearing elements, such as friction bearing bushes or complete
roller bearings, on tubes or tubular portions, by hydraulic
expansion of the tube in the region of the respective element
beyond the limit of elasticity against an elastic prestress
prevailing in the respective elements. The hydraulic expansion is
accomplished by means of a pressure agent probe comprising
effective portions which are associated with the respective
elements to be attached, which are limited by seals and which, via
a first probe borehole system, are connected to a pressure agent
generator. The pressure agent probe also has intermediate portions
between the individual effective portions, which are in contact
with a second probe borehole system, and end portions adjoining the
respective outermost effective portions. The effective portions
form effective regions with the tube, the intermediate portions
form intermediate regions with the tube and the end portions form
end regions with the tube.
From DE 37 26 083 A1 (Balcke-Durr) a pressure agent probe is known
which comprises two independent borehole systems the first of
which, for pressurizing the effective regions, is connected to a
pressure agent generator, and the second system, by being connected
to the intermediate portions, serves to drain off any leakages,
especially when some of the seals fail. The process which may be
carried out with these means is characterized by the pressure
build-up in the effective regions up to a point where the limit of
elasticity of the tubular portions concerned is exceeded, and the
subsequent pressure decreases. Accordingly, the pressure generator
comprises an exit which is directly connected to the first borehole
system of the pressure agent probe.
The essential problem of the prior art processes relates to the
lack of operating safety of the seals, especially with increasingly
larger shaft types to be produced by this process the necessary
pressures increase further.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
process which reduces the risk of seal failure and improves the
service life of the seals.
It is a further object of the invention to provide a pressure agent
probe suitable for carrying out the inventive process, as well as a
suitable pressure generator for carrying out the process, which may
be connected to such a probe.
Pursuant to this object, and others which will become apparent
hereafter, one aspect of present invention resides in subjecting
the effective regions to a high effective pressure suitable for
deforming the tube beyond its limit of elasticity. The intermediate
regions and the end regions, at least in the portions on both sides
of the effective regions and at least while the high effective
pressure is maintained, are subjected to a lower counter pressure
which is higher than the ambient pressure and lower than the
pressure required for deforming the tube beyond its limit of
elasticity. This process in accordance with the invention allows
considerably higher effective pressures to be generated without
having to modify basically the type of seals used, as a rule
standard annular seals, since their failure and wear is primarily
determined by the pressure differential to be sealed, whereas they
are relatively insensitive to an increase in the absolute pressure
level.
By generating, in accordance with the invention, a counter pressure
outside the effective regions which in no way, permanently,
adversely affects the properties of the tubular member exposed in
this region, the seals are prevented from entering to an excessive
extent the sealing gap, as a result of which the service life of
the seals is increased considerably and simultaneously it becomes
possible to increase the pressure further. It is particularly
important to apply the counter pressure to the seals during the
reduction in pressure after the tube expansion, because during this
phase there is a risk of the seal being partially caught in the
sealing gap and being damaged mechanically while the member agent
probe is pulled out of the tubular member.
When using a standard pressure agent generator which builds up the
pressure in an uncontrolled way, it is proposed that, for the
purpose of building up the pressure, a prepressure which is lower
than the effective pressure is initially built up for sealing the
seals in the effective region. This is then followed by a further
pressure build-up in the effective regions and by a build-up of
counter pressure in the intermediate regions and end regions, with
the pressure in the effective regions always being higher than that
in the intermediate and end regions, until the required counter
pressure level has been achieved, with the pressure differential
having to remain below the design limit of the seals. Thereafter, a
further pressure build-up takes place in the effective regions
until the required effective pressure level is reached, with the
higher pressure in the effective regions always ensuring contact of
the seals. For the purpose of reducing the pressure after building
up and maintaining the effective pressure, first, the pressure in
the effective region is reduced to an intermediate pressure level
which is lower than that of the counter pressure in order to
relieve the load on, and allow a spring-back of, the seals.
Thereafter, the pressure in the effective region and the counter
pressure in the intermediate and end regions are reduced
jointly.
Depending on the design of the pressure agent probe, the volumes of
the intermediate and end regions connected to the second borehole
system are relatively large, so that in a further advantageous
embodiment of the process the spaces are filled first with a low
filling pressure whose level is below that of the counter pressure.
This presupposes the existence of a pressure agent generator with
suitable control facilities. In a further embodiment, the process
stage analogously applies to filling the effective region prior to
applying the effective pressure. Depending on the behavior of the
seals, the filling pressure should be set in such a way that it
moves the seals into sealing contact with the tube so that during
the subsequent application of the effective and counter pressures
no uncontrolled deformation of the seals occurs.
The pressure reduction in the effective region on the one hand and
in the end and intermediate regions on the other hand should
preferably take place in a reverse sequence to that of the pressure
build-up, and again the objective has to be to keep the pressure
differentials at the seals as low as possible and to achieve a seal
release by means of a reversed pressure differential.
In an another embodiment of the invention, the above-mentioned
filling pressure is applied even during the insertion of the
pressure agent probe and while the probe is pulled out of the
tubular member so that fluid flushes the seals at a low pressure.
This results in a desirable friction-reducing lubricating effect
for the seals relative to the rough inner wall of the tubular
member.
A pressure agent probe in accordance with the invention for
carrying out the above-mentioned process is characterized in that
outside the outer effective portions limited by seals there are
arranged, at a distance, further seals for forming pressure-loaded
end portions. The end portions are connected to the same system of
longitudinal channels and radial boreholes connected thereto as the
intermediate portions and both borehole systems may be separately
connected to the pressure generating means. Such a pressure agent
probe makes it possible, as explained above, to generate the
required counter pressure in the intermediate and end regions prior
to, or while, applying the effective pressure in the effective
regions.
In a further embodiment of a pressure agent probe in accordance
with the invention the seal pairs of the effective portions are
framed on both sides by at least one counter pressure portion
limited by seals arranged in pairs. The counter pressure portions
are connected in pairs to the second system of longitudinal
channels and radial bores and both borehole systems may be
separately sealingly connected to pressure agent means. In this
way, in accordance with the invention, each effective portion is
associated with separate adjoining portions to which a counter
pressure is applied. Depending on the probe design this arrangement
may be advantageous because it permits the volumes to be subjected
to the counter pressure to be kept very much smaller. The need for
a larger number of seals is thus reduced. This design is
advantageous for probes with particularly pronounced sealing
portions with a larger diameter.
The above-mentioned basic probe designs may be advantageously
combined in such a way as to provide a third borehole system of
longitudinal channels and radial boreholes, with the three existing
systems then being subjected to different pressure levels each,
thereby permitting a double-stage pressure differential for
applying particularly high pressures in the effective regions. The
intermediate pressure regions directly adjoining the effective
regions may be kept short enough for them to be still within the
elements to be attached, and the pressure acting within them
deforms the tube beyond its limit of elasticity.
Pressure generators in accordance with the invention for carrying
out the process in accordance with the invention and for being
connected to the pressure agent probes are characterized in that
one single working or pressure converting piston, in the course of
one operating stroke, loads at least two pressure agent exits with
different pressures. The working piston especially being designed
as a differential piston and by connecting certain dead spaces the
different pressure curves required are generated.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a longitudinal section and cross section of a pressure
agent probe pursuant to the present invention with two borehole
systems; and
FIG. 2 illustrates a longitudinal section and cross section of a
pressure agent probe pursuant to the present invention with three
borehole systems.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a basic probe member 1 which ends in a probe head 2
and onto which there have been slid two sleeves 3, 4 which are
connected to the basic member 1 by soldering, for example. The
basic member 1 consists of an inner tube 5 integral with the probe
head and an outer tube 6. Seal pairs 7, 8 and 9, 10 define
effective regions a.sub.1, a.sub.2 on the sleeves.
Between the effective regions there is an intermediate region
b.sub.2. The probe head 2 is provided with a further seal 11 which,
together with the seal 10, defines an end region c. Via radial
boreholes 12, 13, the effective regions are connected to a central
pressure agent guiding borehole 14 in the basic probe member 1
which penetrates the latter completely and is closed in the probe
head 2 by a plug 15. Via radial boreholes 16, 17, the intermediate
regions b.sub.1, b.sub.2 are connected to a longitudinal channel 18
designed as a groove in the inner tube 5. Via a further radial
borehole 19 the end region c is connected to this same longitudinal
channel 18 whose end is closed by the probe head 2. This second
borehole system serves to build up the counter pressure in all the
intermediate regions b and the end regions c. The central borehole
14 is connected to a higher pressure source of pressure source of
pressure agent 40 to effect the expansion of the tubular member in
the effective regions a.sub.1, a.sub.2, etc., and the channel 18 is
connected to a second pressure source 41 which provides the counter
pressure in the regions b and c.
In FIG. 2, a sleeve 22 has been slid onto a basic probe member 21
in a way so as to be integral with it, which sleeve 22 may be
connected with the tubular member by gluing, shrinking or
soldering, for example. The sleeve 22 carries seals 23, 24 which
are arranged in pairs and define an effective region a.sub.3. The
effective region a.sub.3 is connected to a central pressure agent
channel 26 via a radial borehole 25 which extends vertically
relative to the drawing. The channel 16 is connected to a high
pressure source 42 of pressure agent. Further seals 27, 28 directly
adjoin the seals 23, 24 on the sleeve 22, and define the
above-mentioned counter or intermediate pressure portions d.sub.1,
d.sub.2. Via radial boreholes 29, 30, the intermediate pressure
portions d.sub.1, d.sub.2 are connected to a longitudinal channel
31 in the basic probe member 21 via which a counter pressure has to
be applied from a pressure source 43 if no further boreholes have
been provided in the probe. An intermediate pressure from a
pressure source 44 is applied if the probe has a third system of
radial boreholes 32 which, via a third longitudinal channel 33 are
loaded with a counter pressure for the intermediate and end
regions.
While the invention has been illustrated and described as embodied
in a process for allowing attachment of elements on tubes, it is
not intended to be limited to the details shown, since various
modifications and structural changes may be made without departing
in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention.
* * * * *